This invention relates to an apparatus for removing snow deposited on the wall of a snow generating apparatus, and more particularly relates to such an apparatus which removes snow deposited on the inner surface of the wall of an inner cylinder for growing the snow in the snow generating apparatus and which makes it possible to cause continuous snow generation.
An example of a snow generating apparatus is disclosed, for example, in copending U.S. application Ser. No. 920,194 in the name of Kenji ISONO et al., filed Oct. 17, 1986, now U.S. Pat. No. 4,746,064, issued May 24, 1988. This prior art apparatus will be described with reference to FIG. 2 of the accompanying drawings. This apparatus consists of an erect cooling tower 4', a snow collecting chamber 1' which is connected to the bottom of a cooling tower 4' and the ceiling opening 3' of which is covered by the cooling tower 4', a first cooler 9' connected to the tower 4' by ducts 10' and 11' for drawing off and cooling the internal air of the cooling tower 4' and then returning it to the cooling tower, an inner cylinder 12' which is disposed in such a manner as to extend inside the cooling tower 4' in the longitudinal direction thereof and which is open at the bottom for connection with the opening 3' of the snowfall chamber 1', a circulation pipe 13' which connects the top of the inner cylinder to the lower end, a variable speed blower 14' disposed at an intermediate portion of this circulation pipe 13', a humidifier 15' for receiving air drawn off from inner cylinder 12' through pipe 17' and if desired, diluted by outside air drawn through bypass pipe 18' controlled by valve 20', and supplying vapor through a pipe 16' into the inner cylinder 12' near the lower end portion of the inner cylinder 12', and a snow seed feeder 19 for supplying ice crystals into the inner cylinder near the humidifier 15'. The snow seed feeder 19 has an air compressor 23' supplying air to a further cooler 24' and then through pipe 22' to nozzle 21'.
The first cooler 9' cools the air within the cooling tower 4' so that the inner cylinder 12' and the circulation pipe 13' are cooled indirectly. A cold air stream having a predetermined velocity is formed in the ascending direction inside the inner cylinder 12' by operation of the variable speed blower 14' to pump air downwardly in circulation pipe 13'. The humidifier 15' is actuated to send the vapor into the inner cylinder and to form the cloud. This cloud is carried by the ascending cold air stream and stays in the upper part of the inner cylinder 12' as a supercooled cloud. When the snow seed feeder 19 is operated so as to supply ice crystals into the inner cylinder, they move upward, being carried by the ascending current in the same way as the cloud. When the ice crystals come into contact with the supercooled cloud in the upper part of the inner cylinder 12', a phenomenon which is the same as the natural phenomenon occurs there and snow is formed in the cloud and grows to a size which the ascending current cannot support any longer. Then, snow starts falling and drops into the snow collecting chamber through the opening 3'.
In the process of the growth of the snow in the upper part of the inner cylinder, a snow deposition phenomenon occurs when the floating snow comes into contact with the inner surface of the wall of the inner cylinder, and snow that has once been deposited there grows, and the cloud vapor and the ice crystals that are supplied are consumed by the deposited snow. Accordingly, the amount used for generating snow which falls drops below 30% of the amount fed. Furthermore, the deposited snow exhibits an adiabatic effect, reduces the cooling effect inside the inner cylinder and, hence, reduces the efficiency of the growth of the snow.
This conventional apparatus is therefore subject to the problem that it cannot remove the deposited snow. For this reason, it has not been possible by using the conventional snow generating apparatus to examine the influence of the amount of falling snow upon a testpiece in a continuous snowfall inside the snow chamber or to examine the continuous change of the forms of the snow that is progressively deposited onto the testpiece.